1. Field of the Invention
This invention relates to preamplifiers used in disk drives. In particular, this invention relates to polling a preamplifier within a disk drive to remotely determine pre-established parametric values.
2. Description of the Related Art
Disk drives are known in which one or more read/write heads (e.g., inductive or magnetoresistive (MR) heads) are used to store data on and read data from associated disk media surface. In a typical magnetic media implementation of such a storage device, the preamplifier receives from an associated channel device both data signals to be written onto a disk surface and bilevel control signals used to specify the individual head to be selected for the read or write operation. The preamplifier typically also supplies analog data signals read from a head to the associated channel. A typical preamplifier includes an input preamplifier for amplifying the write data signals received from the associated channel, an output preamplifier for amplifying signals supplied by a read head, a multiplexer for interconnecting the data input and data output internal lines to one of a plurality of read/write heads, and a mode control unit for operating the multiplexer in response to control signals supplied from the channel, typically a chip select signal (CS) for controlling the state of the circuitry within the preamplifier, and a read/write (R/W) signal for specifying either a read operation or a write operation.
The disk drive comprises a controller which executes a microprogram stored in memory (e.g., a read only memory (ROM)) to generate control signals applied to the preamplifier to facilitate the read and write operations. Various components of the disk drive, including the read/write head and the preamplifier, may be manufactured by different suppliers. Consequently, the components may exhibit disparate operating characteristics or feature sets which must be taken into account by the controller when configuring the disk drive.
It is therefore desirable to provide a facility within a disk drive for determining pre-established parametric values of certain components, such as the manufacture of a read/write head or preamplifier, to thereby enable a controller within the disk drive to properly configure the components.